Total joint replacement (TJR) is among the most common Medicare surgical procedures and is increasing among younger patients as well. Because TJR is performed to restore function and to reduce pain and other symptoms, patient-reported outcome (PRO) data is important for patients and clinicians in informing the need for and timing of TJR and in evaluating TJR outcomes. However, joint-specific PRO instruments currently used in TJR research are too long for routine use in clinical care. This project will develop short versions of two joint-specific PRO measures, the 42-item Knee Injury and Osteoarthritis Outcome Score (KOOS) and the 40-item Hip Dysfunction Osteoarthritis Outcome Score (HOOS); a recent Centers for Medicare and Medicaid Services (CMS) Technical Expert Panel on evaluating TJR outcomes recommended consideration of both instruments in performance-based measurement systems. Specifically, the aims of this research are to: (1) Select items for a fixed-length KOOS short form, compare the validity and responsiveness of short and legacy (original) KOOS scales, and prepare a crosswalk to equate short and legacy KOOS scores; and (2) Select items for a fixed-length HOOS short form, compare the validity and responsiveness of short and legacy HOOS scales, and prepare a crosswalk to equate short and legacy HOOS scores. Data will come from the AHRQ-sponsored Function and Outcomes Research for Comparative Effectiveness in TJR (FORCE-TJR) research registry, which has successfully collected PROs from more than 25,000 patients of 150 diverse orthopedic surgeons throughout the US. Pre- and post-TJR data from N=1,200 total knee and N=1,200 total hip replacement patients randomly drawn from the FORCE-TJR database will be analyzed. KOOS and HOOS each measure four joint-specific domains: function, pain, other symptoms and quality of life (QOL). The goal of this research is to develop short forms that are approximately one-third as long as the legacy instruments but which measure all four domains. Multiple criteria, including content representation, empirical data, and clinician and patient inpu, will be considered in selecting items for the short forms by a team that includes researchers with considerable experience in developing short forms from longer PRO instruments, the Principal Investigator (PI) of the FORCE-TJR research grant, and (as advisors) the developer of the KOOS and the HOOS, and surgeon and patient members of the FORCE-TJR Steering Committee. Widely-used psychometric methods such as item response theory modeling and real-data computerized adaptive test (CAT) simulations, which were successfully used in PROMIS and other PRO measurement initiatives, will be applied to provide empirical data used to inform item selection. A variety of cross-sectional and longitudinal tests will be utilized to compare the validity and responsiveness of the short form and legacy KOOS and HOOS scales. User-friendly documentation and crosswalks to equate scale scores on the short forms and legacy instruments will be prepared. Upon completion of this project, brief joint-specific PRO instruments will be available for administration to TJR patients to better inform clinical care decisions and outcomes.